1. Field of the Invention
The present invention relates to a microfluidic device for electrochemically regulating the pH of a fluid therein and a method of regulating the pH of a fluid in the microfluidic device.
2. Description of the Related Art
Microfluidic devices are devices in which an inlet, an outlet, a reaction chamber, or the like are interconnected through microchannels. In addition to the microchannels, a micropump for inducing the flow of fluid, a micromixer for mixing fluids, and a microfilter for filtering fluids, are included in microfluidic devices.
Such devices are widely known in the field and are used in micro-analytic devices, such as a lab-on-a-chip (LOC) that performs a series of biological analytic processes including cell enrichment in samples, cytolysis, purification of biomolecules, amplification and separation of nucleic acids such as a polymerase chain reaction (PCR), and protein separation, hybridization and detection.
The pH levels required to perform each of these biological analytic processes are varied. One such biological analysis process is a conventional pH regulating process that involves adding or removing an acidic solution, a neutral solution, or a buffer solution. However, when adding or removing a pH-adjusting solution to or from a microfluidic device, additional devices and procedures are performed which lead to problems with dilution. Additional devices and procedures can be a serious problem in the microfluidic device when dealing with microscale volumes. Dilution can be a problem when a sample is collected or amplified. Furthermore, the added pH-adjusting material may inhibit subsequent biological analytical processes. In this case, the pH-adjusting material has to be removed.
A method of adjusting the pH using electrolysis is a possible solution to the above conventional problems associated with the injecting pH-adjusting reagent. For example, the pH can be adjusted using an electrolysis device that comprises an anode chamber, a cathode chamber with a membrane that is disposed between the anode and cathode chambers. FIG. 1 is a side sectional view of a conventional microfluidic device for electrochemically regulating the pH of a fluid. In FIG. 1, the conventional microfluidic device includes a cathode 11, an anode 13 and a membrane 15 between the cathode 11 and the anode 13. In the conventional microfluidic device illustrated in FIG. 1, a conducting wire should be additionally installed from the reaction chamber to electrically connect the cathode 11 and the anode 13 to a power supply device 17. However, such electrical connections can limit the miniaturization of the microfluidic device, thereby complicating the manufacturing process, and increasing the costs for manufacturing the microfluidic device.
Meanwhile, micro-structures capable of adsorbing or binding cells are known in the art. Examples of such micro-structures include porous structures, pillar structures, and sieve structures. A porous structure is disclosed in ANALYTICAL BIOCHEMISTRY 257, 95-100 (1998), Integrated Cell Isolation and Polymerase Chain Reaction Analysis Using Silicon Microfilter Chambers by Peter Wilding.
In a microfluidic device used for a lab-on-a-chip, integration between organizations and functions are important for the automated analysis of the entire process. However, integration between regulating the pH and adsorbing or binding cells has not been tried.